Created attachment 411011[details][diff][review]
needs testing
This patch works for me. However, I discovered some strange behaviour:
1) Create an empty folder in the PT.
2) Open the (XUL) bm menu in the the PT and move (d & d) some bookmarks into the newly created folder
3) Open the native bm menu, look for the newly added bookmarks - they're there
4) Open the bm menu in the PT, drag & drop one bm out of the folder
5) Open the native bm menu
--> the folder still contains 2 bookmarks
I can't see how this would be related to the patch, though - need some further investigation.

I see the following with the patch applied on Linux:
1) Create an empty folder in bookmarks menu
2) Drag and drop link onto empty folder
Expected result
1) Link replaces "empty" entry
Actual result
1) Link shows below "empty" entry
When you re-show the bookmarks, "empty" entry has gone.

Created attachment 412414[details][diff][review]
Keep class name and stop the event bubbling
This should address comment #3, asking Ian to get Linux confirmation. Regarding my comment #2, I managed to reproduce this in 2.0 so it doesn't look related to my patch. I guess the native menu sometimes doesn't re-build (or something like that) properly.